1. Field of the invention
The present invention relates to an inhibitor switch for detecting a shift range point of an automatic transmission, and particularly to an inhibitor switch for an automatic transmission which contributes to reduction in the number of components and reduction in a plastic amount.
2. Description of Related Art
U.S. Pat. No. 5,736,701 conventionally proposes an inhibitor switch for detecting a select position of a shift range selector such as a selector lever in an automatic transmission in which a manual valve operates in accordance with the select position of the shift range selector, thereby switching a shift range point.
The inhibitor switch 101 in U.S. Pat. No. 5,736,701 is, as shown in FIG. 3, configured so that a metallic detent plate 103 moving depending on a select position of the select lever and an insulative, plastic stationary contact board 105 are arranged to be as opposed to each other while permitting relative rotation with each other around a manual shaft 107 which is a common shaft of the detent lever 103 and the contact board 105.
An insulative, plastic movable contact board 109 is attached to the detent plate 103. The movable contact board 109 is provided with a plurality of movable contact points 111. For attaching the movable contact board 109 to the detent plate 103, for example, four plastic boss portions 115 which are attached on the movable contact board 109 to extend vertically therefrom are fitted into, for example, four through bores 113 formed to penetrate through the detent plate 103, which are attached by fastening means such as heat caulking or press fitting.
On the other hand, in the stationary contact board 105, a plurality of stationary contact points 117 are provided on one side surface thereof facing the movable contact board 109 by, for example, insert molding.
In the inhibitor switch 101 as constructed above, the detent plate 103 is fixed and fastened to the manual shaft 107 and on the other hand, the stationary contact board 105 is fixed and fastened to a vehicle body side such as a transmission casing. Therefore, when the detent plate 103 rotates and moves with rotation of the manual shaft 107, the movable contact point 111 slides on the stationary contact point 117 while creating a predetermined contact pressure therebetween. By detecting a change of an electrical connection pattern in accordance with a sliding position of the movable contact point 111 to the stationary contact point 117 at this time, a rotational position or the like of the manual shaft 107 is detected and also the shift range position or the like is detected.
In the conventional inhibitor switch 101, however, the metallic detent plate 103 and the plastic stationary contact board 105 are constructed to be as opposed to each other as having a common shaft of both of the metallic detent plate 103 and the plastic stationary contact board 105 as a relative rotation center. Therefore, the stationary contact board 105 requires formation of the shaft support portion 106 and a component (nut) for supporting the stationary contact board 105 is required. In consequence, there is a high demand for an improvement on the inhibitor switch in view of reduction in the number of components and reduction in the plastic amount.
In view of the above, there exists a need for an inhibitor switch for an automatic transmission which overcomes the above mentioned problems in the conventional art. The present invention addresses this need in the conventional art as well as other needs, which will become apparent to those skilled in the art from this disclosure.